1. Field of the Invention
This invention relates to an image forming apparatus and a method for controlling the image forming apparatus and, more particularly, to an image forming apparatus and a method for controlling the image forming apparatus detecting a foreign object attaching to a belt.
2. Description of Related Art
Image forming apparatuses have been known forming images on a label sheet using an intermediate transfer belt. A conventional image forming apparatus transfers toner images in respective colors transferred to a photosensitive drum sequentially to an intermediate transfer belt in an overlapping manner, thereby forming multicolor toner images overlapping the toner images in respective colors on the intermediate transfer belt. The multicolor toner images transferred to the intermediate transfer belt are further transferred onto a label seal by a transfer roller, as disclosed in, e.g., Japanese Patent Application Publication (A1), No. 2015-168216.
Such a prior art image forming apparatus may be suffered from attachment of foreign object such as, e.g., labels to the intermediate transfer belt. Under such a situation, if the foreign object attached to the intermediate transfer belt reaches a cleaning unit or an image forming unit, the cleaning unit or the image forming unit may be damaged or suffered from getting dirty, thereby lowering quality of the images to be formed. Where the quality of the images is graded down, it is required to replace the belt portion including the intermediate transfer belt, or the image forming unit with new one, so that there arises problems such as, e.g., increased inactive times, increased costs, and shortened life time of the parts.
It is therefore an object of the invention to provide an image forming apparatus and a method for controlling the image forming apparatus in which the belt can be stopped before any foreign object on the belt reaches a cleaning unit or an image forming unit.